Correlation between the severity of sleep apnea and upper airway morphology in pediatric and adult patients

Development and Validation of a Nomogram for Predicting Obstructive Sleep Apnea Severity in Children

Purpose

The clinical presentation of Obstructive Sleep Apnea (OSA) in children is insidious and harmful. Early identification of children with OSA, particularly those at a higher risk for severe symptoms, is essential for making informed clinical decisions and improving long-term outcomes. Therefore, we developed and validated a risk prediction model for severity in Chinese children with OSA to effectively identify children with moderate-to-severe OSA in a clinical setting.

Patients and Methods

From June 2023 to September 2023, we retrospectively analyzed the medical records of 367 Children diagnosed with OSA through portable bedside polysomnography (PSG). Predictor variables were screened using the least absolute shrinkage and selection operator (LASSO) and logistic regression techniques to construct nomogram to predict the severity of OSA. Receiver operating characteristic curve (ROC), calibration curve, decision curve analysis (DCA), and clinical impact curve (CIC) were used to determine the discrimination, calibration, and clinical usefulness of the nomogram.

Results

A total of 367 children with a median age of 84 months were included in this study. Neck circumference, ANB, gender, learning problem, and level of obstruction were identified as independent risk factors for moderate-severe OSA. The consistency indices of the nomogram in the training and validation cohorts were 0.841 and 0.75, respectively. The nomogram demonstrated a strong concordance between the predicted probabilities and the observed probabilities for children diagnosed with moderate-severe OSA. With threshold probabilities ranging from 0.1 to 1.0, the predictive model demonstrated strong predictive efficacy and yielded improved net benefit for clinical decision-making. ROC analysis was employed to classify the children into high and low-risk groups, utilizing the Optimal Cutoff value of 0.39.

Conclusion

A predictive model using LASSO regression was developed and validated for children with varying levels of OSA. This model identifies children at risk of developing OSA at an early stage.

Medical Treatment of Obstructive Sleep Apnea in Children

Obstructive sleep apnea (OSA) is characterized by recurrent complete or partial obstruction of the upper airway. The prevalence is 1-4% in children aged between 2 and 8 years and rising due to the increase in obesity rates in children. Although persistent OSA following adenotonsillectomy is usually associated with obesity and underlying complex disorders, it can also affect otherwise healthy children. Medical treatment strategies are frequently required when adenotonsillectomy is not indicated in children with OSA or if OSA is persistent following adenotonsillectomy. Positive airway pressure treatment is a very effective modality for persistent OSA in childhood; however, adherence rates are low. The aim of this review article is to summarize medical treatment options for OSA in children.

The Reliability of Three-Dimensional Landmark-Based Craniomaxillofacial and Airway Cephalometric Analysis

Cephalometric analysis is a standard diagnostic tool in orthodontics and craniofacial surgery. Today, as conventional 2D cephalometry is limited and susceptible to analysis bias, a more reliable and user-friendly three-dimensional system that includes hard tissue, soft tissue, and airways is demanded in clinical practice. We launched our study to develop such a system based on CT data and landmarks. This study aims to determine whether the data labeled through our process is highly qualified and whether the soft tissue and airway data derived from CT scans are reliable. We enrolled 15 patients (seven males, eight females, 26.47 ± 3.44 years old) diagnosed with either non-syndromic dento-maxillofacial deformities or OSDB in this study to evaluate the intra- and inter-examiner reliability of our system. A total of 126 landmarks were adopted and divided into five sets by region: 28 cranial points, 25 mandibular points, 20 teeth points, 48 soft tissue points, and 6 airway points. All the landmarks were labeled by two experienced clinical practitioners, either of whom had labeled all the data twice at least one month apart. Furthermore, 78 parameters of three sets were calculated in this study: 42 skeletal parameters (23 angular and 19 linear), 27 soft tissue parameters (9 angular and 18 linear), and 9 upper airway parameters (2 linear, 4 areal, and 3 voluminal). Intraclass correlation coefficient (ICC) was used to evaluate the inter-examiner and intra-examiner reliability of landmark coordinate values and measurement parameters. The overwhelming majority of the landmarks showed excellent intra- and inter-examiner reliability. For skeletal parameters, angular parameters indicated better reliability, while linear parameters performed better for soft tissue parameters. The intra- and inter-examiner ICCs of airway parameters referred to excellent reliability. In summary, the data labeled through our process are qualified, and the soft tissue and airway data derived from CT scans are reliable. Landmarks that are not commonly used in clinical practice may require additional attention while labeling as they are prone to poor reliability. Measurement parameters with values close to 0 tend to have low reliability. We believe this three-dimensional cephalometric system would reach clinical application.

Gasotransmitter modulation of hypoglossal motoneuron activity

Obstructive sleep apnea (OSA) is characterized by sporadic collapse of the upper airway leading to periodic disruptions in breathing. Upper airway patency is governed by genioglossal nerve activity that originates from the hypoglossal motor nucleus. Mice with targeted deletion of the gene Hmox2, encoding the carbon monoxide (CO) producing enzyme, heme oxygenase-2 (HO-2), exhibit OSA, yet the contribution of central HO-2 dysregulation to the phenomenon is unknown. Using the rhythmic brainstem slice preparation that contains the preBötzinger complex (preBötC) and the hypoglossal nucleus, we tested the hypothesis that central HO-2 dysregulation weakens hypoglossal motoneuron output. Disrupting HO-2 activity increased the occurrence of subnetwork activity from the preBötC, which was associated with an increased irregularity of rhythmogenesis. These phenomena were also associated with the intermittent inability of the preBötC rhythm to drive output from the hypoglossal nucleus (i.e. transmission failures), and a reduction in the input-output relationship between the preBötC and the motor nucleus. HO-2 dysregulation reduced excitatory synaptic currents and intrinsic excitability in inspiratory hypoglossal neurons. Inhibiting activity of the CO-regulated H2S producing enzyme, cystathionine-γ-lyase (CSE), reduced transmission failures in HO-2 null brainstem slices, which also normalized excitatory synaptic currents and intrinsic excitability of hypoglossal motoneurons. These findings demonstrate a hitherto uncharacterized modulation of hypoglossal activity through mutual interaction of HO-2/CO and CSE/H2S, and support the potential importance of centrally derived gasotransmitter activity in regulating upper airway control.

X-Ray Cephalometric Analysis of the Effects of Angle Class II and III Malocclusion on the Upper Airway Width and Hyoid Position between Parents and Children of Uygur Nationality

Objective

The objective of this paper is to analyze the effect of angle class II and III malocclusion on the sagittal diameter of the upper airway between parents and children of Uygur nationality and to compare the degree of influence.

Methods

29 Uygur adolescents with malocclusion and their fathers (mothers) were selected as our subjects via X-ray cephalometric radiograph to analyze the difference between the upper airway sagittal dimension and normal occlusion and compare the influence of malocclusion on the upper airway between parents and children.

Results

Compared with normal group, the vertical distance from the hyoid point to orbital-ear plane (H-FH) and vertical distance from hyoid point to the mandibular plane (H-MP) in angle class II malocclusion elevated signally, while the vertical distance from hyoid point to anterior cervical plane (H-VL), PNS-UPW, H-FH, and H-MP decreased significantly; compared with normal group: the distance between the posterior nasal spine and the upper pharynx wall (PNS-UPW), H-FH, and H-MP in angle class III malocclusion visually reduced, while PAS, and horizontal distance from the hyoid point and center point of sella turcica to orbital-ear foot (H-S), increased markedly. The impact of class II malocclusion on parents' U-MPM was greater than their children.

Conclusion

The oropharyngeal space of upper airway becomes smaller and hyoid shifts downwards due to class II malocclusion. Class III malocclusion results in decreased nasopharyngeal gap with hyoid to shift upward. The influence of class II malocclusion on the upper pharyngeal tract of parents was greater than their children.

Computational fluid dynamic analysis of the nasal respiratory function before and after postero-superior repositioning of the maxilla

Morphological changes in the upper airway and the resulting alteration in the nasal respiratory function after jawbone repositioning during orthognathic surgery have garnered attention recently. In particular, nasopharyngeal stenosis, because of the complex influence of both jaws, the effects of which have not yet been clarified owing to postero-superior repositioning of the maxilla, may significantly impact sleep and respiratory function, necessitating further functional evaluation. This study aimed to perform a functional evaluation of the effects of surgery involving maxillary repositioning, which may result in a larger airway resistance if the stenosis worsens the respiratory function, using CFD for treatment planning. A model was developed from CT images obtained preoperatively (PRE) and postoperatively (POST) in females (n = 3) who underwent maxillary postero-superior repositioning using Mimics and ICEM CFD. Simultaneously, a model of stenosis (STENOSIS) was developed by adjusting the severity of stenosis around the PNS to simulate greater repositioning than that in the POST. Inhalation at rest and atmospheric pressure were simulated in each model using Fluent, whereas pressure drop (ΔP) was evaluated using CFD Post. In this study, ΔP was proportional to airway resistance because the flow rate was constant. Therefore, the magnitude of ΔP was evaluated as the level of airway resistance. The ΔP in the airway was lower in the POST compared to the PRE, indicating that the analysis of the effects of repositioning on nasal ventilation showed that current surgery is appropriate with respect to functionality, as it does not compromise respiratory function. The rate of change in the cross-sectional area of the mass extending pharynx (α) was calculated as the ratio of each neighboring section. The closer the α-value is to 1, the smaller the ΔP, so ideally the airway should be constant. This study identified airway shapes that are favorable from the perspective of fluid dynamics.

Impact of Upper Airway Characteristics on Disease Severity and CPAP Therapy in Chinese Patients With OSA: An Observational Retrospective Study

Objective

The characteristics of the upper airway (UA) are important for the evaluation and treatment of obstructive sleep apnea (OSA). This study aimed to investigate the association of UA characteristics with OSA severity, titration pressure, and initiation of and 3-month compliance with continuous positive airway pressure (CPAP).

Methods

This retrospective study included consecutive patients examined using a semi-quantitative UA evaluation system (combination with physical examination and awake endoscopy) during 2008–2018 at the Department of Respiratory and Critical Care Medicine, Peking University First Hospital. First, the differences in UA characteristics were compared between patients with simple snorers and mild OSA and those with moderate-to-severe OSA. Then, the effect of UA characteristics on the initiation to CPAP therapy and 3-month adherence to CPAP was conducted.

Results

Overall, 1,002 patients were included, including 276 simple snorers and patients in the mild OSA group [apnea-hypopnea index (AHI) <15] and 726 patients in the moderate-to-severe OSA group (AHI ≥15). Tongue base hypertrophy, tonsillar hypertrophy, mandibular recession, neck circumstance, and body mass index (BMI) were independent risk factors for moderate-to-severe OSA. Among those patients, 119 patients underwent CPAP titration in the sleep lab. The CPAP pressures in patients with thick and long uvulas, tonsillar hypertrophy, lateral pharyngeal wall stenosis, and tongue hypertrophy were higher than those of the control group (P < 0.05, respectively). The logistic regression analysis showed that nasal turbinate hypertrophy, mandibular retrusion, and positive Müller maneuver in the retropalate and retroglottal regions were independent predictors for the initiation of home CPAP treatment.

Conclusion

Multisite narrowing and function collapse of the UA are important factors affecting OSA severity, CPAP titration pressure, and the initiation of home CPAP therapy. Clinical evaluation with awake endoscopy is a safe and effective way for the assessment of patients with OSA in internal medicine.

Much Ado about Sleep: Current Concepts on Mechanisms and Predisposition to Pediatric Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a form of sleep-disordered breathing characterized by upper airway collapse during sleep resulting in recurring arousals and desaturations. However, many aspects of this syndrome in children remain unclear. Understanding underlying pathogenic mechanisms of OSA is critical for the development of therapeutic strategies. In this article, we review current concepts surrounding the mechanism, pathogenesis, and predisposing factors of pediatric OSA. Specifically, we discuss the biomechanical properties of the upper airway that contribute to its primary role in OSA pathogenesis and examine the anatomical and neuromuscular factors that predispose to upper airway narrowing and collapsibility.

Exploration of the Influences of Temporary Velum Paralysis on Auditory-Perceptual, Acoustic, and Tomographical Markers

Purpose To better understand hypernasality (HN), we explored the relations between velopharyngeal orifice, auditory perception of HN, and acoustic-spectral measures in an in vivo within-subject design: (a) with a normally functioning velum as the control condition and (b) with a temporarily paralyzed velum as the experimental condition. Method The velum of eight volunteers was injected with ropivacaine hydrochloride (Naropin) in the area of the levator veli palatini and tensor veli palatini muscles to induce temporary velopharyngeal inadequacy (VPI) and HN. Sustained [a] and [i] and oronasal text readings were recorded, and 3D cone-beam computed tomography images of the vocal tract were built before and during velar anesthesia. Differences between conditions and correlations in normal-to-numb differences between velopharyngeal cross-sectional area (VP_area), mean ratings of HN severity, and nine acoustic-spectral measures were determined. Results Three subjects already had some incomplete velopharyngeal closure in the control condition. Temporary motor nerve blockage of the velum (increased VP_area) was accomplished in seven subjects, leading to increased HN and changes in three acoustic-spectral measures. Furthermore, significant correlations only emerged between VP_area, HN, and Model_Kataoka. Conclusions In most of the participants, it was possible to temporarily increase the velopharyngeal orifice to investigate HN while controlling other speech variables and cephalic morphology. Although this study was exploratory and its are findings preliminary, it provided additional evidence for the possible clinical value of Model_Kataoka, A ₃-P ₀, and B _F1 for the objective measurement of VPI or HN.

Adult obstructive sleep apnoea: Pathogenesis, importance, diagnosis and imaging

Obstructive sleep apnoea (OSA) is a serious worldwide health problem. Moderate-to-severe OSA has been found in up to 50% of men and 25% of women in the middle-aged population. It results in a fourfold increase in all causes of mortality. The prevalence of OSA is underestimated, partly due to absence of symptoms but also lack of knowledge amongst the population at large as well as sectors of the medical profession. Imaging, performed predominantly by clinicians and research scientists, has been integral to evaluating the anatomical basis of OSA. Increased nasal resistance and a narrowed and elongated oropharynx lead to increased collapsibility of the upper airway, predisposing to airway collapse and apnoea during sleep when there is reduction in tone of the pharyngeal dilator muscles. Unfortunately, a significantly narrowed upper airway is usually ignored by radiologists: it is not part of their reporting 'check-list'. The imaging findings in the upper airway that are strongly associated with OSA and its sequelae in various organ systems are discussed. Imaging can strongly suggest OSA; the diagnosis requires a polysomnogram for confirmation. Treatment of moderate-to-severe disease is primarily with positive airway pressure applied by a nasal or oral mask which splints the upper airway. Although highly effective, compliance is limited and other treatment modalities are increasingly being utilized.

Effects of bicuspid extractions and incisor retraction on upper airway of Asian adults and late adolescents: A systematic review

OBJECTIVES

This systematic review aimed to assess the effects of bicuspid extractions and incisor retraction on airway dimension, hyoid position and breathing of adults and late adolescents.

METHODS

The review was conducted according to PRISMA guidelines. Eight databases including PubMed, EMBASE, Web of Science and Scopus were searched to August 2018. Minimum age of participants was 16 years. The intervention was dual-arch bicuspid extractions with incisor retraction. Outcomes were airway dimension, hyoid position and breathing assessment.

RESULTS

All nine publications meeting inclusion criteria were from Asia. They were divided into three Asian subregions. All East Asian lateral cephalometric studies reported anteroposterior airway narrowing at the oropharynx and sometimes the hypopharynx. However, the narrowing was small, comparable to measurement errors, and highly variable. Two out of three East Asian computed tomography (CT) studies described reductions in airway dimensions. The single functional breathing study showed increased simulated flow resistance after incisor retraction in East Asians. South Asian studies had mixed findings, with some reporting significant airway narrowing. The single study from West Asia found no significant airway or hyoid changes.

CONCLUSIONS

Airway response to bicuspid extractions and incisor retraction varied substantially when assessed with cephalometry. CT measurements present larger effect sizes and smaller variations, providing stronger evidence of airway narrowing. Orthodontic extractions for incisor retraction may be more frequently indicated in Asia, and East Asians seem particularly susceptible to airway narrowing and postero-inferior hyoid movement with incisor retraction. Better designed CT studies are needed for confirmation due to small effect size and large variability.

Computational fluid dynamics study of the pharyngeal airway space before and after mandibular setback surgery in patients with mandibular prognathism

The purpose of this study was to investigate the relationship between the pressure drop in the pharyngeal airway space (ΔP_PAS) and the minimum cross-sectional area (minCSA) of the pharyngeal airway before and after mandibular setback surgery using computational fluid dynamics, in order to prevent iatrogenic obstructive sleep apnoea. Eleven patients with mandibular prognathism underwent bilateral sagittal split osteotomy for mandibular setback. Three-dimensional models of the upper airway were reconstructed from preoperative and postoperative computed tomography images, and simulations were performed using computational fluid dynamics. ΔP_PAS and the minCSA of the pharyngeal airway were calculated, and the relationship between them was evaluated by non-linear regression analysis. In all cases, the minCSA was found at the level of the velopharynx. After surgery, ΔP_PAS increased significantly and the minCSA decreased significantly. The non-linear regression equation expressing the relationship between these variables was ΔP_PAS=3.73×minCSA^-2.06. When the minCSA was <1cm², ΔP_PAS increased greatly. The results of this study suggest that surgeons should consider bimaxillary orthognathic surgery rather than mandibular setback surgery to prevent the development of iatrogenic obstructive sleep apnoea when correcting a skeletal class III malocclusion.

Obstructive sleep apnoea pathogenesis from mild to severe: Is it all the same?

Obstructive sleep apnoea (OSA) is a common disorder caused by not only an impaired upper airway anatomy (i.e. anatomically narrow/collapsible airway), but also by several non-anatomical factors. In this review, we summarise what is known about how each of the pathological factors that cause OSA vary according to disease severity as measured by the apnoea-hypopnoea index. Our synthesis of the available literature indicates that most of the key factors that cause OSA vary with disease severity. However, there is substantial heterogeneity such that the relative contribution of each of these traits varies both between patients and within different severities of disease. These differences likely contribute to variable efficacy of many non-continuous positive airway pressure treatments and inconsistencies in responses with regard to different OSA severities at baseline.

Evaluation of obstructive sleep apnea in pediatric patients with facio-craniostenosis: a brief communication

PURPOSE

This study aimed to evaluate our experience in treating cranio-maxillo-mandibular malformations with hypoplasia of the upper and middle third of the face. We wished to determine a new diagnostic path involving a new clinical questionnaire for obstructive sleep apnea (OSA) evaluation, which we have developed by merging existing tests, literature findings, and our clinical experience to obtain a high level of information with minimal cost. This questionnaire is an improvement of the other anamnestic tests in the literature.

METHODS

The study was carried out on 17 pediatric patients affected by syndromic craniofacial malformations and treated with surgical advancement of the middle third of the face, associated with or without upper third advancement, through osteodistraction. We used the obstructive airway child test (OACT) for clinical evaluation. The OACT is an OSA assessment test based on questions proposed to the patient's relatives. All patients underwent polysomnography for instrumental assessment of OSA. These patients were also required to have a computed tomography scan for surgical planning. At the start of the treatment, 11 patients had severe OSA, 4 patients had moderate OSA, and 2 patients had slight OSA.

RESULTS

At the end of the treatment, 6 patients had slight OSA and 11 patients had no OSA; these data were confirmed with OACT and polysomnography.

CONCLUSIONS

Based on our results, we suggest the following flowchart: OACT for OSA clinical evaluation; CT scan for evaluation of the volume of the rhinoropharyngeal air column, anatomical obstruction detection, and surgical planning; and polysomnography for diagnostic confirmation.

A case series on lung deposition analysis of inhaled medication using functional imaging based computational fluid dynamics in asthmatic patients: effect of upper airway morphology and comparison with in vivo data

CONTEXT

Asthma affects 20 million Americans resulting in an economic burden of approximately $18 billion in the US alone (Allergies and Asthma Foundation 2000; National Center for Environmental Health (NCEH) 1999). Research studies based on differences in patient-specific airway morphology for asthma and the associated effect on deposition of inhaled aerosols are currently not available in the literature. Therefore, the role of morphological variations such as upper airway (extrathoracic) occlusion is not well documented.

OBJECTIVE

Functional imaging based computational fluid dynamics (CFD) of the respiratory airways for five asthmatic subjects is performed in this study using computed tomography (CT) based patient-specific airway models and boundary conditions.

METHODS

CT scans for 5 asthma patients were used to reconstruct 3D lung models using segmentation software. An averaged inhalation profile and patient-specific lobar flow distribution were used to perform the simulation. The simulations were used to obtain deposition for BDP/Formoterol® HFA pMDI in the patient-specific airway models.

RESULTS

The lung deposition obtained using CFD was in excellent agreement with available in vivo data using the same product. Specifically, CFD resulted in 30% lung deposition, whereas in vivo lung deposition was reported to be approximately 31%.

CONCLUSION

It was concluded that a combination of patient-specific airway models and lobar boundary conditions can be used to obtain accurate lung deposition estimates. Lower lung deposition can be expected for patients with higher extrathoracic resistance. Novel respiratory drug delivery devices need to accommodate population sub-groups based on these morphological and anatomical differences in addition to subject age.

Treating obstructive sleep apnea with hypoglossal nerve stimulation

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) is a common disorder characterized by recurrent pharyngeal collapse secondary to sleep-induced hypotonia of peri-pharyngeal structures. Therapy for OSA is sometimes poorly tolerated and not always effective. The current study reviews a new treatment modality, hypoglossus stimulation, recently evaluated by multiple physiological studies and currently assessed by several clinical studies.

RECENT FINDINGS

A phase-I, implantable hypoglossus nerve stimulation multicenter study was published in 2001. Significant reduction in apnea-hypopnea index (AHI) was reported in seven of the eight implanted OSA patients, but technical faults precluded prolonged follow-up. Over the past 2 years, three new hypoglossus nerve stimulation systems have been evaluated in more than 60 OSA patients. In adequately selected patients, a more than 50% reduction in AHI was observed. Usually, a decrease in OSA severity from moderate-severe to mild-minimal can be achieved.

SUMMARY

Ongoing research, including recent initiation of a large multicenter phase-III study, suggests that hypoglossus nerve stimulators are likely to be available as a new treatment modality within a few years. Additional data are needed to define which OSA patients are most likely to benefit from hypoglossus nerve stimulation. Continuous refinement of electrodes design is likely to improve stimulation efficacy in coming years.

Measurements of normal upper airway assessed by 3-dimensional computed tomography in Chinese children and adolescents

OBJECTIVE

To establish normative data of upper airway dimensions in Chinese children and adolescents by age and sex.

METHODS

CT-scans of 281 Chinese children and adolescents (140 girls, 141 boys) aged from 6 to 18 years (yr) were selected among the patients who visited in Department of Oral and Maxillofacial Surgery from September 2009 to August 2010. Child was defined as 6-12 yr, and adolescent as 13-18 yr. All the subjects were divided into 4 groups according to age as 6-9, 10-12, 13-15 and 16-18. The upper airway was divided into four distinct anatomic regions: the nasopharynx, the palatopharynx, the glossopharynx and the epiglottic region. Using 3-dimension image processing software, the minimal cross-sectional area with its sagittal diameter and transversal diameter, length and volume of upper airway segmentations were measured.

RESULTS

There was no difference in all parameters of segmentations between genders in children. In adolescents the differences of airway parameters were evident between genders. Male adolescents' upper airway were bigger and longer than female's. Volumes and lengths of segmentations were increased with age in male and female respectively.

CONCLUSIONS

Norms for upper airway in Chinese children and adolescents assessed by 3-D reconstruction computed tomography have been established. Volume and other dimension of upper airway are increased with age. Significant sex dimorphisms in upper airway dimension are evident in adolescents.